What horn signal should a train operator use to request police assistance when entering a station?

In the context of train operations, the horn signals are used to communicate specific messages to other personnel, including requests for assistance. The signal that is used to request police assistance when entering a station is the long-short-long-short pattern. This particular sequence is distinctive and recognized by operators and personnel as a request for immediate attention from law enforcement.

When a train operator uses the long-short-long-short horn signal, it serves as a clear and universally understood communication tool to alert police about the train's approach and need for assistance. The structured nature of these horn signals is vital in ensuring that responses can be immediate and effective, especially in potentially urgent situations.

Other options might serve different purposes or indicate different messages, so understanding the specific meanings behind horn signals is crucial for safe and efficient train operations. The long-short-long-short signal is specifically designated for police assistance, making it the correct choice in this scenario.